Current Measles Risk for Adults
Global measles cases increased sharply in 2023 and 2024, with the WHO and CDC reporting outbreaks in both under-vaccinated regions and pockets of low coverage in wealthy countries. The CDC noted that measles is one of the most contagious diseases, with a basic reproduction number of 12 to 18, meaning one infected person can infect 12 to 18 others in a fully susceptible population. In the United States, the CDC confirmed over 250 individual cases in 2024, linked to international travel and under-vaccinated communities. Adults born before 1957 are generally considered immune due to widespread circulation of the wild virus, but adults born after that year who lack documented vaccination or immunity may be at risk.
Two doses of the measles-mumps-rubella vaccine provide about 97 percent protection against measles after exposure, according to the CDC. One dose provides about 93 percent protection. Vaccine effectiveness remains high over decades, but waning immunity is a documented phenomenon in some populations, particularly when vaccination coverage drops below the herd immunity threshold of roughly 95 percent. Outbreaks in highly vaccinated settings, such as the 2019 New York City outbreak, showed that even with high two-dose coverage, pockets of susceptibility can fuel rapid spread. The CDC and WHO emphasize that the MMR vaccine is a live attenuated vaccine and is not associated with autism, a claim thoroughly debunked by numerous large-scale studies.
Who Should Get a Measles Booster as an Adult
Adults at increased risk include international travelers, healthcare workers, college students, and people living in or near outbreak zones. The CDC recommends that adults in these groups who lack evidence of immunity receive at least one dose of the MMR vaccine, and in some outbreak settings, a second dose. Evidence of immunity includes written documentation of vaccination, laboratory confirmation of immunity or past infection, or birth before 1957. The CDC does not recommend routine booster doses for the general adult population who have received two documented doses, but it does recommend a booster for adults at risk during outbreaks or before international travel to areas with active measles transmission.
For adults unsure of their vaccination status, serologic testing for measles IgG antibodies can confirm immunity without unnecessary vaccination. The CDC states that receiving an additional dose of MMR vaccine is safe for people who may already be immune. The Advisory Committee on Immunization Practices periodically reviews adult immunization schedules, and the most recent adult schedule update reaffirmed the two-dose childhood series and the targeted booster approach for at-risk adults. This guidance aligns with the WHO position that outbreak response vaccination campaigns should prioritize high-risk groups and close contacts.
How to Get a Measles Booster and What to Expect
Adults can receive the MMR booster at pharmacies, primary care clinics, and public health departments across the United States. Major pharmacy chains such as CVS, Walgreens, and Rite Aid offer MMR vaccinations through their in-store clinics, often with walk-in availability and insurance billing. The cost without insurance typically ranges from 40 to 100 dollars per dose, but the CDC's Vaccines for Adults program and many insurance plans cover the cost when medically indicated. The WHO maintains a list of prequalified vaccine manufacturers, including Sanofi, GlaxoSmithKline, and Merck, which supply the MMR vaccine globally. The CDC's Vaccine Adverse Event Reporting System continuously monitors safety data, and the most recent reviews confirm that the MMR vaccine has a well-established safety profile in adults.
Side effects of the MMR booster in adults are generally mild and include soreness at the injection site, low-grade fever, and a temporary rash. Serious adverse events are rare, with the CDC reporting febrile seizures in a small fraction of recipients, mostly in young children rather than adults. The CDC and FDA continuously update the